Low energy electron-molecule collision studies in gas phase

Chakraborty, Dipayan (2019) Low energy electron-molecule collision studies in gas phase. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Dipayan Chakraborty (14RS010)) 14RS010.pdf - Submitted Version Restricted to Repository staff only Download (7MB)

Abstract

The goal of this project is to study the absolute DEA cross-sections along with kinetic energy and angular distribution of the fragment ions resulting from low energy electron molecule collisions. The cross-section study provides us information about the location of TNI state in the Franck-Condon transition window with respect to the ground state. Kinetic energy distribution of the fragments provides the kinetic energy release (KER) by the system and the threshold energy required for the process whereas, the angular distribution provides the associated symmetry of the TNI state. Hence, kinematically complete study of low energy electron molecule collision is carried out. The thesis has been arranged in the following way. In chapter 1, the background of the electron-molecule interaction studies, DEA and IPD studies are discussed. The theoretical background of DEA cross-section, angular distribution and kinetic energy distribution of the fragment negative ions are also discussed. This chapter contains the basics of the whole work presented in the thesis. Chapter 2 contains the instrumentation part where two different spectrometers, which are used to study the results presented in the thesis, are discussed. Out of these, the absolute DEA cross-section measurement spectrometer is developed starting from scratch, hence discussed in details. Another one is the velocity slice imaging spectrometer which is discussed briefly. Chapter 3 and 4 contains the absolute DEA cross-section studies of difluoromethane and chiral molecules: camphor, fenchone and propylene oxide. In chapter 5, detailed dissociation dynamics of DEA to ammonia molecule is discussed by using the velocity slice imaging technique. Chapter 6 contains the IPD dynamics of CO molecule by using the velocity slice imaging technique. Chapter 7 contains the future aspect of the work presented in the thesis. Here, the formation of isolated cold molecules and clusters by replacing the effusive beam with supersonic gas-jet is discussed briefly.

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